Indianapolis Colts running back Trent Richardson (34) has had a run time making an impact for his new team after his earlier trade from the Cleveland Browns. / Pat Lovell, USA TODAY Sports

by Jarrett Bell, USA TODAY Sports

by Jarrett Bell, USA TODAY Sports

Peyton Manning used to come to Gillette Stadium for his toughest mental chess exams.

So often, he was overmatched.

Bill Belichick played the cat-and-mouse games with a savvy, veteran New England Patriots defense that frustrated Manning by forcing him off his spot, as they put it, and out of rhythm.

That was a long time ago.

It seems that the tables have turned.

Belichick's 20th-ranked defense, young and injury-depleted, is the one that seems overmatched as it heads into Sunday night's marquee matchup against the Denver Broncos.

And not only because Manning comes to town with the league's most prolific offense.

A defense that that has been dogged by adversity all season -- including the losses of Vince Wilfork, Jerod Mayo and Tommy Kelly to season-ending injuries -- will take a short-handed secondary into a game against a wide-open offense directed by the NFL's most cerebral quarterback.

And another sign came Saturday, when defensive back Justin Green was promoted from the practice squad.

One way or another, the battered secondary looms as a large issue when facing a quarterback on pace to set a single-season passing record and a team averaging nearly 40 points.

Yet beyond the physical, there's the mental challenge.

Regardless of who's out there -- and during New England's Monday night loss at the Carolina Panthers, it was rookies Logan Ryan and Duron Harmon in the secondary for extensive stretches -- the Patriots cannot simply line up and play against Manning.

If the Patriots can't play a sophisticated game that disguises coverages before the snap, Manning will eat that defense alive.

"You better do a good job of it, or it's going to be a long day," Belichick said.

Belichick knows it won't be as simple as taking away one key weapon and building a plan from there, although he used Talib to shut down New Orleans Saints tight end Jimmy Graham in a victory against that high-powered offense last month.

With Denver's passing game, handling Wes Welker in the slot and wideout Demaryius Thomas -- a catch-and-run terror -- will be huge priorities.

Yet it all starts with dealing with Manning. With his quick release, he is still one of the toughest quarterbacks in the league to sack and deadly against the blitz.

That's why the mental chess match with disguised coverages is such a key.

"He sees the blitz, calls a tear screen to Demaryius Thomas and he goes 75 yards for a touchdown," Belichick said. "You can be in whatever you want to be in, but if they have a play to beat it, and it's well-executed, which it frequently is with Denver, you're just playing right into their hands.

"They've been waiting all day to run the play against that situation. You tell them, 'Ok, here were are, we're going to be in Cover 2 zone, go ahead and run your best play,' well, they will."

Belichick's defense, with just three players who have started each game this season (Chandler Jones, Rob Ninkovich and Devin McCourty), is obviously evolving, as it has been forced to adjust to the injuries.

On the half-full ledger, it has cut down the rate of big plays that was such a liability last year, and like last year proven to be turnover-hungry. And as Manning pointed out this week, it has been stingy in the red zone.

Contrary to the yardage it has allowed (354.9 per game), the Patriots rank sixth in the league for scoring defense.

Yet the defense will need more than a few wrinkles to contend with Manning.

"You have to play good team defense," Belichick said. "That's all there is to it."

Last Monday, the unit couldn't stop Cam Newton from driving the Panthers the length of the field in crunch time for what was ultimately the game-winning touchdown.

It's too bad that Wilfork, Mayo and Kelly can't come back this season.

Given what's left, can the Patriots win a championship with their defense?

It's too early to definitively declare anything.

Yet the matchup against Manning could show the Patriots exactly where they stand.

Other items to ponder as Week 12 rolls on:

Three intriguing storylines

*Put up or shut up. For all the votes of confidence coming out of Dallas this week -- Cowboys owner Jerry Jones confirmed that coach Jason Garrett's status is safe for next year, maintained he would want no one running his beleaguered defense than coordinator Monte Kiffin and declared that he has done some of his best work as GM the past few years -- there's still the matter of the huge game at the Meadowlands. It's one thing that the New York Giants (4-6) have clawed back into the race in the shaky NFC East with four consecutive victories. More essential: What were the Cowboys (5-5) able to accomplish during the bye week to help an ailing defense that was humiliated at New Orleans?

With just four sacks in three games, maybe the extra time afforded DeMarcus Ware in nursing a quad injury and D-tackle Jason Hatcher's return from a neck injury will offset the loss of middle linebacker Sean Lee. Interestingly, while Jones has taken his share of swipes at the Giants over the years, this time the bulletin board material came from the other direction. After New York safety Will Hill insinuated that Dallas wideout Dez Bryant doesn't thrive against physical coverage, cornerback Terrell Thomas followed that up by guaranteeing a Giants victory. So the put-up-or-shut-up theme works both ways.

*Remember me? Bruce Arians, who stepped in as interim coach last season while Indianapolis Colts coach Chuck Pagano underwent treatment for leukemia, was so proficient that he directed the team to the playoffs and won Coach of the Year honors. He also earned his own head coaching job with the Arizona Cardinals, set to host the Colts in a reunion game Sunday. And just like last year, Arians is getting into a nice flow. The Cardinals (6-4) have won three consecutive games to play themselves into the thick of the playoff race. The defense has been impressive, demonstrating no drop-off in the switch from coordinator Ray Horton to Todd Bowles.

And lately, Arians' offense has come up to speed to complement the defense. Two keys: Carson Palmer has reduced the turnovers and Michael Floyd has emerged as a legit threat to counter star wideout Larry Fitzgerald. During the three-game streak, Palmer has thrown just two picks. Before that, he threw multiple picks in five consecutive games. Arians has a way of bringing out the best in quarterbacks -- Ben Roethlisberger, Peyton Manning, Andrew Luck -- so Palmer's surge might not be coincidental. If he can protect the ball.

*Zebra Watch. After last weekend's controversies, the NFL's brain trust is undoubtedly keeping its fingers crossed for a nice, quiet weekend on the officiating front. Then again, the week already includes one ironic and high-profile non-call -- Saints defensive end Akiem Hicks wasn't flagged for the blow to Atlanta Falcons quarterback Matt Ryan's head Thursday night, which resembled the hit that San Francisco 49ers linebacker Ahmad Brooks was penalized for (and fined, $15,750) after blasting Drew Brees. In any event, there's no shortage of teaching moments. With the one-game suspension of umpire Roy Ellison (which has been appealed by the referees union), the officials have a fresh reminder of how to respond if -- as people speaking on behalf of Ellison contend -- Washington Redskins tackle Trent Williams provoked the ump into a vulgar response by cursing Ellison first ... and capping the remark with a racial slur. Ellison should have thrown his penalty flag for a 15-yard infraction or ejection.

As for the other major incident at Carolina, when the flag thrown by back judge Terrence Miles for Luke Kuechly's apparent pass interference against Gronkowski was picked up, there are multiple lessons. Although the NFL backed the non-call, perhaps there's a lesson about officials being talked out of calls; as former NFL officiating director Mike Pereira told me, it was a case that should have been reviewed by instant replay. Regardless, let's also hope that, most significantly, officials don't run off the field as Clete Blakeman's crew did on Monday night, without sticking around to explain such a questionable call -- to the coaches and players, fans in the stands and viewers alike.

*Who's hot: Roethlisberger. After playing his best game of the season last weekend against the Detroit Lions, the Pittsburgh Steelers quarterback will get a tougher challenge Sunday against the Browns in Cleveland -- where the conditions will be frigid, the winds swirling and a stingy defense awaits, yet to allow a 200-yard passer all season. Even so, Big Ben will enter on a roll. With buzz in the air last week that suggested he will want out of Pittsburgh after the season, Roethlisberger (who maintains that he wants to stay) responded by demonstrating that there's hope yet in running Todd Haley's offense. He shredded the Lions defense for 367 passing yards, with four TDs and zero picks, to notch another fourth-quarter comeback win. And for the first time in more than two years, he also earned a Player of the Week award.

*Pressure's on: Trent Richardson. Since the big trade in September, the Colts running back has averaged 2.8 yards per rush, and hasn't had a run longer than 8 yards in more than a month. Now he's nagged by a calf injury, too. The deal that involved shipping a first-round pick to Cleveland might ultimately pay off for the Colts, who value Richardson when needing power runs. But for the most part, his lack of explosion is bogging down an offense trying to stay potent through so many key losses (Reggie Wayne, Dwayne Allen, Vick Ballard, Ahmad Bradshaw). At least there's a change-up option in Donald Brown, who brings the acceleration that has produced the big-play runs for the offense -- and the possibility of replacing Richardson as the starter.

*Rookie watch: Kyle Long. The right guard from Oregon has played a key role in the significantly upgraded Chicago Bears offensive line ... and now he can show his big brother, Chris, just how well it's flowing when Chicago visits the Eddie Jones Dome in St. Louis on Sunday. With Chris lining up at left end, the brothers likely won't have one-on-one engagements. But they will be close enough to swap sweat in the trenches and Little Brother could draw some double-team assignments and slide protections. The bigger picture is just as intriguing with a strength-on-strength matchup pitting their respective units. The Bears allowed 44 sacks in 2012, eighth-most in the league. Yet under new coach Marc Trestman and new coordinator, the rebuilt line has allowed just 16 sacks, third-fewest in the NFL. Now comes an ultimate test in a noisy dome against the Rams defense that leads the NFL in sacks-per-play.*

*Stomach for an upset: Minnesota Vikings at Green Bay Packers. The Packers haven't won a game since spanking the Vikings at the Metrodome in Week 8. But that was with Aaron Rodgers, and Green Bay has lost three consecutive games since their star quarterback broke a collarbone. There's no sympathy from Minnesota, a dreaded NFC North rival that would take special delight in kicking the Packers while they're down.

Then again, perhaps Adrian Peterson, questionable with a groin injury, will heal to create something special in what will mark his 100th NFL game. Peterson ranks fourth in the NFL with 851 rushing yards, but by his standards it has been a sub-par season. He has had just three 100-yard games, and was held to 60 by the Pack a few weeks ago. With 9,700 career yards and 85 rushing TDs, though, he needs just 67 yards to surpass Barry Sanders' mark as the third-most rushing yards through 100 games (after Eric Dickerson's 10,818 and Jim Brown's 10,403). Let's see if he can mark the milestone with a monster game.

*Next man up: The Committee. Panthers left end Charles Johnson, a foundation block for one of the best front seven units in the NFL, can't be replaced by one player as he nurses a sprained medial collateral ligament. Carolina heads into Sunday's game at the Miami Dolpphins expecting to use a platoon system of backups -- alternating Wes Horton, Mario Addison and Frank Alexander. Horton, an undrafted rookie from Southern California, is the best run-defender of the group, while Addison, the most experienced of the group in his third season is the best edge rusher. Addison, used in spot duty, ranks fourth on the team with 10 quarterback pressures.

The Panthers might have caught a bit of a break in facing Miami, which has allowed an NFL-high 41 sacks and is down three starters (including Jonathan Martin and Richie Incognito). Still, losing Johnson -- whose injury occurred on a leg whip by Patriots tackle Marcus Cannon, who was fined $15,750 -- is crucial. Not

only does Johnson rank third in the NFC with 8 1/2 sacks, his value as a run-defender was illuminated during the second half Monday night when New England's power rushing attack kicked into gear after the injury.

*Stat's the fact: Washington Redskins linebacker London Fletcher's iron man streak has hit another milestone. Fletcher, a 16th-year veteran, played in his 250th consecutive game last weekend, and made his 209th consecutive start -- surpassing Derrick Brooks' mark as most-ever by a linebacker. All this from a man who entered the league as an undrafted free agent from Division III John Carroll University.